Figure 3. Photomicrographs of tooth germs removed from mice on E17d (a-f) and tooth germs cultured for 10 days after E17d (E17d-C10) (g-l). (a-c, g-i) WT mouse. (d-f, j-l) Hyp mouse. (b,e,h,k) Higher magnifications of the boxed areas in (a,d,g,j), respectively. (c,f,i,l) In situ hybridization. (a-f) Polarized odontoblasts cannot be seen. (c,f) No reactivity for OC mRNA is shown. (g-l) Most of the odontoblasts have differentiated into the secretory phase, and thin dentin matrix can be observed [between arrowheads in (h) and (k)]. (i,l) Reactivity for OC mRNA in odontoblasts. AB, ameloblasts; D, dentin; DP, dental papilla; EO, enamel organ; OB, odontoblasts; PA, pre-ameloblasts; PO, pre-odontoblasts.